All 911 turbo rebuild are not the same!
10-05-2004, 02:09 AM
#1
Rennlist Lifetime Member
Thread Starter
All 911 turbo rebuild are not the same!
This is a post I put over on the 996TT board. Thought you would like see the contrast to the other motors.
I thought I would share with you the typical day in an engine build. Not many people have dove into the TTs motors for several reasons. One I think because most are still under warranty. The need will arise sooner than later. There are some natural wear items and as the HP goes up so should the insurance policies. AKA, rods, studs etc. Everything has a purpose and a goal in mind. The one thing unlike the motors from years past is the 996TT motor is old and new technology combined. When that happens there is always a different way of doing things. This means a battery of tools that is required. We have always been able to slip by on the old stuff with very little mandatory tools. If you plan on building a 996TT motor be prepared to spend 3-4K in tools alone. This is if you already have the equipment for the older motors. I will out line as I go along the newer procedures and things that require a different tool.
Removing the motor is not any more difficult than any 993TT motor. More wires, more lines, more weight and coolant. Be prepared for one heck of a mess. I rarely make a mess, all bets are off on these motors. Even for me.
The amount of crap on the top of these motors is amazing. The maze of lines, additions and supports is staggering. The 993TT is nothing. It will take you a day if you are familiar with them just to clear the motor to the long block. Keep a keen eye out for the order that you removed things. If you go to assemble and do not reverse the order you will spend the next 2 days trying to figure out how in the heck the lines went under all the crap. I will post pictures of the motor on the table when I find what I did with them.
Once you have cleared the motor of the intake etc then you can start into the meat of the motor. You will remove the valve covers to expose the cams.
Notice the mess of coolant and oil draining, even 3 days later!
The next step is to remove tensioners, holders and cams. You will want to invest in the manuals. If you do not follow the order you run the risk of damaging the cams and or sprockets.
Notice the center of the top tappets. There are two sections to these tappets. The center section and the out edges. As computer deems necessary based on load, TPS, RPM etc the cams will switch from 3mm lift to 10 mm lift. If you look at the picture above you will notice the 3 sections to each lobe. This is the equivalent of 2 cams in one. The sections of the tappet will drop out exposing the desired section to achieve a specific lift. At the same time the cams are also advancing from the sprocket on the nose of the intake cams. It is a very elaborate system that relies on oil to act as a hydraulic coupler. This is what activates and moves these items. Never use anything other than the weight the factory recommends.
The next step is to remove the housing and remove the cylinder assembly. These items will simply pull off exposing the pistons and head studs only.
From here the motor splits like any other 911 case. The 14 case studs and a nut. The outer bolts and the case splits in half exposing the crank, oil pump intermediate shaft and chains.
This picture shows the original pump compared to the new GTIIIR pump to be installed. Notice the second pick up on the bottom. The new pump goes in without modification to the case. If you use high performance rods you WILL need to profile the pump 20 thousands. Notice the red ink on the installed GTIIIR pump. This is the profiling area. If you don’t profile the pump expect to be back in there. The rods will hit the pump as the big end passes on the stroke.
The newest gig from Porsche is a clear silicone that sets in 10 minutes. I am not and never have been a fan of silicone in any Porsche motor. I cleaned the case halves with a soft wire brush, steamed the cases then applied loctite 574 to the case halves. Notice the case through bolts on the lower channels. These are now sealed with O rings and the case has a beveled edge to seat the rings down when the case halves are closed. Also never forget the orings on the oil pump. For those of you reading, notice the oil pump bolts?
Next is the assembly of the head studs. I have chosen to go with an updated heavy duty version. These are not available from Porsche. These are aircraft strength and quality. Notice the coating.
Once the head studs are installed and set to 150mm from spigot you can preassemble and set the cylinder assembly. This is were things get very different from the past. In the older motors each cylinder was separate and assembly could be done in any order. In the new setup there is no way to install the pistons of you do not follow the order and have the special tools. You will want to press the liners out of the block and install new seals. I replaced the old style rubber ones on the liner with Viton, while the others remain a different compound. The liners must be pressed in. Keep in mind for final assembly the center liner has to be pressed in on the car with the special tools. I will post those tomorrow. For those that think you can buck the system and do it without. Forget it. Not happening. I promise. BTDT.
I thought I would share with you the typical day in an engine build. Not many people have dove into the TTs motors for several reasons. One I think because most are still under warranty. The need will arise sooner than later. There are some natural wear items and as the HP goes up so should the insurance policies. AKA, rods, studs etc. Everything has a purpose and a goal in mind. The one thing unlike the motors from years past is the 996TT motor is old and new technology combined. When that happens there is always a different way of doing things. This means a battery of tools that is required. We have always been able to slip by on the old stuff with very little mandatory tools. If you plan on building a 996TT motor be prepared to spend 3-4K in tools alone. This is if you already have the equipment for the older motors. I will out line as I go along the newer procedures and things that require a different tool.
Removing the motor is not any more difficult than any 993TT motor. More wires, more lines, more weight and coolant. Be prepared for one heck of a mess. I rarely make a mess, all bets are off on these motors. Even for me.
The amount of crap on the top of these motors is amazing. The maze of lines, additions and supports is staggering. The 993TT is nothing. It will take you a day if you are familiar with them just to clear the motor to the long block. Keep a keen eye out for the order that you removed things. If you go to assemble and do not reverse the order you will spend the next 2 days trying to figure out how in the heck the lines went under all the crap. I will post pictures of the motor on the table when I find what I did with them.
Once you have cleared the motor of the intake etc then you can start into the meat of the motor. You will remove the valve covers to expose the cams.
Notice the mess of coolant and oil draining, even 3 days later!
The next step is to remove tensioners, holders and cams. You will want to invest in the manuals. If you do not follow the order you run the risk of damaging the cams and or sprockets.
Notice the center of the top tappets. There are two sections to these tappets. The center section and the out edges. As computer deems necessary based on load, TPS, RPM etc the cams will switch from 3mm lift to 10 mm lift. If you look at the picture above you will notice the 3 sections to each lobe. This is the equivalent of 2 cams in one. The sections of the tappet will drop out exposing the desired section to achieve a specific lift. At the same time the cams are also advancing from the sprocket on the nose of the intake cams. It is a very elaborate system that relies on oil to act as a hydraulic coupler. This is what activates and moves these items. Never use anything other than the weight the factory recommends.
The next step is to remove the housing and remove the cylinder assembly. These items will simply pull off exposing the pistons and head studs only.
From here the motor splits like any other 911 case. The 14 case studs and a nut. The outer bolts and the case splits in half exposing the crank, oil pump intermediate shaft and chains.
This picture shows the original pump compared to the new GTIIIR pump to be installed. Notice the second pick up on the bottom. The new pump goes in without modification to the case. If you use high performance rods you WILL need to profile the pump 20 thousands. Notice the red ink on the installed GTIIIR pump. This is the profiling area. If you don’t profile the pump expect to be back in there. The rods will hit the pump as the big end passes on the stroke.
The newest gig from Porsche is a clear silicone that sets in 10 minutes. I am not and never have been a fan of silicone in any Porsche motor. I cleaned the case halves with a soft wire brush, steamed the cases then applied loctite 574 to the case halves. Notice the case through bolts on the lower channels. These are now sealed with O rings and the case has a beveled edge to seat the rings down when the case halves are closed. Also never forget the orings on the oil pump. For those of you reading, notice the oil pump bolts?
Next is the assembly of the head studs. I have chosen to go with an updated heavy duty version. These are not available from Porsche. These are aircraft strength and quality. Notice the coating.
Once the head studs are installed and set to 150mm from spigot you can preassemble and set the cylinder assembly. This is were things get very different from the past. In the older motors each cylinder was separate and assembly could be done in any order. In the new setup there is no way to install the pistons of you do not follow the order and have the special tools. You will want to press the liners out of the block and install new seals. I replaced the old style rubber ones on the liner with Viton, while the others remain a different compound. The liners must be pressed in. Keep in mind for final assembly the center liner has to be pressed in on the car with the special tools. I will post those tomorrow. For those that think you can buck the system and do it without. Forget it. Not happening. I promise. BTDT.
10-05-2004, 02:09 AM
#2
Rennlist Lifetime Member
Thread Starter
This is the cylinder assembly with the center liner out.
This is a liner out of the block. Notice the updated seal.
Install the base gasket.
Number 2 and 5 preset ready for the cylinder assembly to be placed on.
I will continue with more pictures tomorrow. I don’t want to bore anyone. I do however want to share a few more things. I had mentioned premature wear on the thrust bearing and on the intermediate shaft thrust. The picture hear shows at 40K miles the brass is visible on the thrust collar. Odd to say the least.
Here are a few of the cam tools need for the cams. Special holders and wrenches.
Heads, cam housing, cylinder assembly, valve covers and more. I have a high pressure steamer that will clean anything. Notice no cosmline on this motor.
This is a liner out of the block. Notice the updated seal.
Install the base gasket.
Number 2 and 5 preset ready for the cylinder assembly to be placed on.
I will continue with more pictures tomorrow. I don’t want to bore anyone. I do however want to share a few more things. I had mentioned premature wear on the thrust bearing and on the intermediate shaft thrust. The picture hear shows at 40K miles the brass is visible on the thrust collar. Odd to say the least.
Here are a few of the cam tools need for the cams. Special holders and wrenches.
Heads, cam housing, cylinder assembly, valve covers and more. I have a high pressure steamer that will clean anything. Notice no cosmline on this motor.
10-05-2004, 08:44 AM
#4
Addict
Rennlist Member
Rennlist Member
Hmmm, my engine didn't come nearly as clean! 
These are great pictures and descriptions. Keep 'em coming Stephen!!!!
Toby
These are great pictures and descriptions. Keep 'em coming Stephen!!!!Toby
10-05-2004, 04:53 PM
#6
PorschePHD,
You sure know your business. I am interested in buying a 911 turbo and know that I will keep it a very long time and it will be modified. These are reasons enough to learn the lesson your giving as it will influence what year car to buy. It seems like these engines a far more complex than the earlier cars like the late 80's-early 90's. Thanks for the info. I think this is one thread that will benefit many.
You sure know your business. I am interested in buying a 911 turbo and know that I will keep it a very long time and it will be modified. These are reasons enough to learn the lesson your giving as it will influence what year car to buy. It seems like these engines a far more complex than the earlier cars like the late 80's-early 90's. Thanks for the info. I think this is one thread that will benefit many.
Trending Topics
10-05-2004, 11:31 PM
#8
Rennlist Lifetime Member
Thread Starter
Blitx,
It is give and take. The older engine while cheaper in areas are also more in areas. The abuse the newer can take compared to the older is sifferent and so on. It is all about end goals and needs..oh and wants. I love them all. No matter what Porsche motor I touch, I always feel at home
Thanks Geoffrey! Wait util our new building is done. My new engine room is 3 times larger!! I can't wait.
It is give and take. The older engine while cheaper in areas are also more in areas. The abuse the newer can take compared to the older is sifferent and so on. It is all about end goals and needs..oh and wants. I love them all. No matter what Porsche motor I touch, I always feel at home
Thanks Geoffrey! Wait util our new building is done. My new engine room is 3 times larger!! I can't wait.
10-06-2004, 12:09 AM
#9
Track Day
Join Date: Oct 2003
Location: Surf City, U.S.A.
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
Doctor Porsche,
Thank you for sharing.
From your statements, it sounds like the motor had about 40k on it. It appears that most of the hardware was reusable, with the exception of the bearings and head studs? Any other changes?
How much horsepower and how much boost are you planning on running? Any other changes? Turbos? Intercooler? Cams?
Thanks again.
Tinker
Thank you for sharing.
From your statements, it sounds like the motor had about 40k on it. It appears that most of the hardware was reusable, with the exception of the bearings and head studs? Any other changes?
How much horsepower and how much boost are you planning on running? Any other changes? Turbos? Intercooler? Cams?
Thanks again.
Tinker
10-06-2004, 01:55 AM
#11
Rennlist Lifetime Member
Thread Starter
Ok, time for more pics…
We talked about the pressing in and out of the liners. Below is a picture of the procedure for pressing it out. I use a hydraulic press to do this. Notice part of the Porsche tool in the liner.
The next picture show the liners on the outer cylinders and the factory spacer tool behind the cylinder block.
This is a picture of one of the two circlip tools you will need. There is an art to using these and making them help rather than hurt. Install it wrong and the circlip will pop off and roll into the newly sealed case. You guess it, hope you are good at fishing.
Next is the picture of the piston being compressed in the ring and supported by the Porsche OEM tool.
There are other ways to do this procedure, but to be honest the OEM tool keeps it simple. You will not loose time by continuously slipping past the rings.
One of the interesting things about the 996TT pistons that is unlike any Porsche piston from the past is the second ring land. The groove has a dowel as seen in the picture that prevents the ring from spinning in the cylinder. When reringing the piston I highly recommend you place the oil scraper ring away from the bottom of the cylinder. This will prevent unnecessary smoking from time to time.
Once the cylinder assembly is installed on the spacers you will need one of these. Once again this is about an 800.00 tool.
Here is the tool installed and live at work.
This picture shows the headgasket. When installing notice the orientation. There is a face of the gasket. The gasket is a three part gasket riveted together. There is only one way to install this.
Here are the heads back on the motor and torques to spec.
One nice upgrade is the use of the older style chain housing gaskets. The 993 style has about a .5mm more rubber on it than its newer brother for the 996TT. The gasket on the left is the 993 version, the gasket on the right is the 996TT gasket. They are interchangeable. I also suggest this to the chain tensioner gaskets.
We talked about the pressing in and out of the liners. Below is a picture of the procedure for pressing it out. I use a hydraulic press to do this. Notice part of the Porsche tool in the liner.
The next picture show the liners on the outer cylinders and the factory spacer tool behind the cylinder block.
This is a picture of one of the two circlip tools you will need. There is an art to using these and making them help rather than hurt. Install it wrong and the circlip will pop off and roll into the newly sealed case. You guess it, hope you are good at fishing.
Next is the picture of the piston being compressed in the ring and supported by the Porsche OEM tool.
There are other ways to do this procedure, but to be honest the OEM tool keeps it simple. You will not loose time by continuously slipping past the rings.
One of the interesting things about the 996TT pistons that is unlike any Porsche piston from the past is the second ring land. The groove has a dowel as seen in the picture that prevents the ring from spinning in the cylinder. When reringing the piston I highly recommend you place the oil scraper ring away from the bottom of the cylinder. This will prevent unnecessary smoking from time to time.
Once the cylinder assembly is installed on the spacers you will need one of these. Once again this is about an 800.00 tool.
Here is the tool installed and live at work.
This picture shows the headgasket. When installing notice the orientation. There is a face of the gasket. The gasket is a three part gasket riveted together. There is only one way to install this.
Here are the heads back on the motor and torques to spec.
One nice upgrade is the use of the older style chain housing gaskets. The 993 style has about a .5mm more rubber on it than its newer brother for the 996TT. The gasket on the left is the 993 version, the gasket on the right is the 996TT gasket. They are interchangeable. I also suggest this to the chain tensioner gaskets.
10-06-2004, 10:47 AM
#12
Racer
Join Date: Jun 2003
Location: CO
Posts: 497
Likes: 0
Received 0 Likes
on
0 Posts
Stephen, this is all good info but could scare the 996TT guys away. I guess Porsche had to make it harder to rebuild the engine since you were getting too good at rebuilding the others. Also the need for more tools, not that you didn't have enough already. I'm sure you enjoyed rebuilding it and I believe that is your motor in your car? So how long will the cylinders last? Sounds like more money to rebuild that beast than the others because of labor. Do you think once you have done a couple and learned the best way to do it that you will feel confident in rebuilding them for others? Pretty soon Porsche owners might have to ship the motor back to Stuttgart for a motor rebuild...LOL
10-06-2004, 11:12 AM
#13
Rennlist Lifetime Member
Thread Starter
I think Porsche did take a route of doing it their way with special tools to make it harder for the independent guy to do this. I think from a performance and the durability standpoint these motors are not even in the same league as the air-cooled. Everything as a whole, with the few exceptions I mentions look better and last longer because of newer designs and certainly the cooling aspect. No 993TT motor would hold together this length of time making this power. You assume I haven't been into these motors before. I just thought I would share a build with you guys. I am doing them for other customers. Most are rod changes so the cost is not terrible. Mostly labor. Not sure if Porsche will ever make it that bad. I think they tried with this, but there will be guys like me doing it. As far as I know there are few out there that are doing these, aside from the dealer.
10-06-2004, 11:45 AM
#15
Racer
Join Date: Jun 2003
Location: CO
Posts: 497
Likes: 0
Received 0 Likes
on
0 Posts
Sorry for assuming you hadn't been in them before, yeah that motor should be better all around vs. a 930 motor no question. Rebuilding a 930 should be cake compared to that one. This should give confidence to others rebuilding a 930 motor. What design issues have you come across that need addressing with that motor?